89-91 - Polskie Stowarzyszenie Biomateriałów
89-91 - Polskie Stowarzyszenie Biomateriałów
89-91 - Polskie Stowarzyszenie Biomateriałów
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oth tests the differences between groups are not statistic<br />
significant. The specimen no.5 shows the excessive values<br />
in the nanoindentation. We did not find their cause, hence<br />
we excluded it from the calculation of the mean elastic<br />
modulus.<br />
acknowledgements<br />
The research project has been supported by the research<br />
plan MSM 6840770012 “Transdisciplinary research in the<br />
field of the biomedical engineering II”.<br />
References<br />
[1] J. Vondrova, P. Ruzicka, R. Sedlacek, et al., The Effect of Alcohol<br />
Administration on the Bone Mechanical Properties. Proceedings of<br />
the 22nd DAS, Parma (2005), 106-107.<br />
[2] Y. H. An, R. A. Draughn, Mechanical Testing of Bone and the<br />
Bone-Implant Interface, CRC Press LLC, Boca Raton, FL, 2000,<br />
263.<br />
expeRimental assessment<br />
of IonIzIng RadIaTIon loW<br />
doSES ImPaCT on TEETh<br />
Development<br />
N.N.CHESHKO, H.A.BERLOV, I.O.POHODENKO-CHUDAKOVA*<br />
byeloruSSiAn StAte MedicAl uniVerSity, MinSK, belAruS<br />
33-239, PuShKin AV.; Po box 190;<br />
220092, MinSK, belAruS<br />
*MAilto: iP-c@yAndex.ru<br />
[Engineering of Biomaterials, <strong>89</strong>-<strong>91</strong>, (2009), 8-9]<br />
Introduction<br />
Scientific grounds of solving post-Chernobyl medical,<br />
biological, ecological, economic, social and other problems<br />
remain as an important task for researchers working in different<br />
fields of science.<br />
Our research purpose is to study ionizing radiation low<br />
doses (IRLD) in the laboratory experiment.<br />
materials and methods<br />
The experiments were carried out on 27 not thoroughbred<br />
white female rats. They and their litter were irradiated<br />
at the Institute of Radiobiology NAS RB by the «Gammarid-192/120<br />
unit» (Gamma-defectoscope «Gammarid»<br />
manufactured by the «Isotop» Enterprise, Leningrad) unit<br />
at 110mR/h exposition power from the 1st gestation day up<br />
to material selection on the 16th, 18th, 20th gestation day<br />
and on the 1st and 3rd postnatal day. The absorbed dose<br />
was 0,38–0,56Gy. The controls were not irradiated.<br />
The specimens were fixed in 10% neutral formalin then<br />
embedded in paraffin according to the standard method.<br />
Sagittal «serial-selective» sections [1] were stained with<br />
hematoxylin and eosin, picrofuchsin after van Gieson sum<br />
content of DNA and RNA, which was evaluated by 5-mark<br />
scale, revealed by the method of Einarson, elastic fibers<br />
- by Hart, argyrophil ones - by Bilshovsky (H.Berlov’s<br />
modification) [2].<br />
Proliferative activity was determined according to the<br />
method of A.Kazantseva [3]. The number of cellular layers<br />
also was counted. The square, thickness and length of teeth<br />
germs (TGs) were measured with «Bioscan – AT» (Model<br />
was constructed in Central Scientific-Research Laboratory,<br />
Medical Institute, Minsk) automatic image analyser. The<br />
measurements were carried in each case of control and<br />
experiment 10 times as a minimum. In all, 8329 histological<br />
specimens of foetuses’ and new-born rats’ heads were<br />
prepared, 2197 of them showing tooth germs. The data were<br />
analysed by variation statistics with the Student’s test.<br />
Results<br />
While studying IRLD impact on odontogenesis we have<br />
revealed some unknown before structures in tooth germs.<br />
Thus, we described «concentric structures» in dental lamina<br />
and in the inner enamel epithelium, its appearance was<br />
delayed in experimental foetuses by IRLD action; pillowlike<br />
thickenings in the inner enamel epithelium in controls;<br />
inverted into mesenchyme dental buds in experimental rats’<br />
foetuses, focal mesenchyme cell invasion into oral cavity.<br />
We also have described undermembrane (underenameloblast)<br />
cellular layer for the first time. Cyst formation due<br />
to radiation exposure was revealed in the inner enamel<br />
epithelium.<br />
IRLD suppressed considerably the proliferative activity<br />
of tooth germ cells. Total mitotic index in all age animals’<br />
groups turned out to be lower than the respective indices in<br />
the controls. Thus, in the experimental 16-day old foetuses<br />
these values were 7,61±1,32‰, in the controls 25,84±0,45‰<br />
(p